Vertical alignment of printed carbon nanotubes by multiple field emission cycles

The effect of field emission cycles on printed carbon nanotubes was investigated using scanning electron microscopy and current–voltage measurement. After multiple emission cycles, the printed nanotubes irreversibly deformed to orient themselves parallel to the field direction and, from them, remarkably enhanced emission image with good uniformity was demonstrated. Corresponding gradual decrease in the field emission threshold and increase of field enhancement factor $\left(\beta \right)$ were also observed during field emission cycles.